Method of fabricating composite multi-metallic billets useful for metal working operations

ABSTRACT

Method of fabricating compacted composite multi-metallic billets for metal working operations having at least two discrete metal constituents disposed in predetermined desired positional disposition therein. Included therein is the formation of at least a pair of discrete powdered metal receiving cavities of predetermined configuration within a deformable shell, introduction of powdered metal therein and isostatic compaction to predetermined desired density without appreciable change in the relative physical disposition of the metals, one to the other.

United States Patent [191 Hurst 1 1 METHOD OF FABRICATING COMPOSITE MULTl-METALLIC BILLETS USEFUL FOR METAL WORKING OPERATIONS [75] lnven orz Alvin L. Hurst, Lower Burrell, Pa.

[73] Assignee: Aluminum Company of America, Pittsburgh, Pa.

[22] Filed: Oct. 10, 1972 [2]] Appl. No.: 296,006

[52] US. Cl 29/420, 29/191.2, 29/D1G. 31 [51] Int. Cl. B22f 3/04 [58] Field of Search 29/420, 4205, DIG. 31,

29/DIG. 47, 191.2, 182.1, 182.2; 75/208 R, 226

[56] References Cited UNITED STATES PATENTS 1 1/1961 Smith et a1 29/420 5 12/1962 Brauchler 29/191.2 X

3,279,917 10/1966 Ballard et a1. 29/DlG. 31 3,285,714 1l/1966 Davies et a1. 29/182.l 3,373,003 3/1968 Schreiner 29/182.2 3,678,567 7/1972 Manilla et a1..... 29/420.5

R20,46O 8/1937 Jeffrey 425/112 X [111 3,780,418 [4 Dec. 25, 1973 2,517,902 8/1950 Luebkeman 264/91 2,695,231 11/1954 Causley 75/208 R 3,146,099 8/1964 Teja 75/208 R 3,335,001 8/1967 Drew et a1. 75/208 R 3,391,444 7/1968 Haller 29/420.5 3,447,230 6/1969 Bargainnier et a1. 29/420.5

Primary Examiner-Richard J. Herbst Assistant ExaminerD. C. Reiley, lll Att0rneyRobert E. lsner et a1.

[5 7] ABSTRACT Method of fabricating compacted composite multimetallic billets for metal working operations having at least two discrete metal constituents disposed in predetermined desired positional disposition therein. Included therein is the formation of at least a pair of discrete powdered metal receiving cavities of predetermined configuration within a deformable shell, introduction of powdered metal therein and isostatic compaction to predetermined desired density without appreciable change in the relative physical disposition of the metals, one to the other.

6 Claims, 12 Drawing Figures p E i 2 I A I 1, a, I g, 1, I a

PATENTEDUEBZSIQR 3,780,418

FIG. IE

FIG. ID

FIG. IB FIG. IC

FIGZA METHOD OF. FABRICATING COMPOSITE MULTl-METALLIC BILLETS USEFUL FOR METAL WORKING OPERATIONS This invention relates to the fabrication of compacted powdered metal billets for metal working operations and particularly to the fabrication of composite billets formed of at least two discrete metal constitucuts of differing metallurgical characteristics selectively disposed in predetermined desired positional disposition both internally and externally thereof.

The fabrication of certain types of non-planar composite multi-metallic products, such as rods, bars, tubes or shapes, from two or more discrete metals or metal alloys of differing metallurgical characteristics by conventional practices is both relatively expensive and of limited utility because of the difficulties attendant formation of properly contoured and constituted starting billets that permit direct production of the desired composite multi-metallic product of predetermined configuration and character by extrusion or other conventional fabrication operation.

The invention may be briefly described as an improved method of fabricating compacted composite multimetallic billets for metal working operations formed of at least two discrete metal constituents of differing metallurgical characteristics selectively disposed in predetermined desired positional disposition both internally and externally thereof. In its broader aspects, the subject invention includes the positioning of an elongate hollow partition member of a first predetermined cross-sectional configuration within a closed end deformable shell of a second predetermined crosssectional configuration and of at least substantially commensurate length therewith, with the dependent end of such partition member disposed in abutting relation with the closed end defining wall portion of the deformable shell member to cooperatively define at least a pair of discrete powered metal receiving cavities of predetermined cross-sectional and longitudinal configuration therein. Finely divided particles of metal of differing metallurgical character are then selectively introduced into said receptacles to substantially fill the same. After removal of such partition member, which .serves to introduce the partition engaging surfaces of said metal particles into intimate interfacially engaged relation at a defined interface therebetween, the deformabel shell and its contents are subjected to isostatic compaction, as by application of hydrostatic pressure, to compact said finely divided metals to a predetermined desired density without any appreciable change in the relative physical positional disposition of such metals, one to the other. ln its narrower aspects, the subject invention is particularly directed to the fabrication of composite multi-alloy billets for the extrusion of selectively clad aluminum base alloy products and includes the positioning of an elongate thin walled hollow core member of a first predetermined cross-sectional configuration within a closed end deformable shell of predetermined cross-sectional configuration and of at least substantially commensurate length therewith, with the open end of the core member disposed in abutting relation with the closed end defining wall portion of the shell member to form a pair of discrete aluminum base alloy powder receiving cavities therein. Subsequent to the selective introduction of discrete finely divided aluminum base alloy powders of differing metallurgical character into such cavities, the core member is axially removed and the deformable shell member and its contents is hydrostatically subjected to cold isostatic compaction to produce a self-supported compact or billet having said discrete aluminum base alloy powders compacted to predetermined density without appreciable change in the relative physical positional disposition thereof permitting, without further treatment such as sintering or the like, extrusion thereof to form a composite or clad product of predetermined internal and external character.

Among the advantages of the subject invention is the permitted simple and inexpensive formation of composite multi-metallic billets of predetermined discrete internal and external configuration to permit the direct production of composite multi-metallic products of predetermined character in a subsequent metal working operation. Another advantage of the subject invention is the permitted fabrication, at markedly reduced cost and expense, of compacted composite billets of aluminum base alloy powders of predetermined desired configuration suitable for direct utilization in subsequent metal working operations. A further advantage of the subject invention is the permitted fabrication of cold compacted composite multi-alloy billets for the extrusion of selectively clad aluminum base alloy products from at least two discrete aluminum base alloy powders of differing metallurgical character that dispenses with the need for sintering and which permits production of an acceptably bonded clad product of desired internal and external configuration upon subsequent extrusion thereof.

The primary object of this invention is the provision of an improved method for fabricating composite multi-metallic billets of predetermined desired internal and external configuration for metal working operations.

Another object of this invention is the provision of an improved method for fabricating composite multimetallic billets from at least two discrete powdered metal constituents of differing metallurgical character and having such differing metal constituents disposed in predetermined desired configuration both internally and externally thereof.

A further object of the invention is the provision of an improved method for forming composite multi-alloy billets from discrete aluminum base alloy powders for fabrication of selectively clad aluminum base alloy products that dispenses with the need for sintering thereof.

Still another object of the invention is the provision of an improved method of fabrication of selectively clad extruded aluminum base alloy products from discrete aluminim base alloy powders having predetermined desired external and internal configuration at the bonded interface thereof.

Other objects and advantages of this invention will be apparent from the following portions of the specification and from the appended drawings which schematically illustrate, in accordance with the mandate of the patent statutes, certain presently preferred operations deemed by the inventor to incorporate the principles of this invention.

Referring to the drawings FIGS. 1(a) through 1(e) schematically illustrate, in vertical section, features of a preferred sequence of steps empolyable in the fabrication of multi-metallic billets in accord with the principles of this invention.

FIGS. 2(a) through 2(e) are horizontal sections as taken on the line 2-2 through FIGS. 1(a) through 1(e), respectively.

FIG. 3 is a horizontal section, similar to FIG. 2(c), schematically illustrative of fabrication of an extrusion billet having a core portion of a cross sectional configuration different from that of the outer or cladding portions.

FIG. 4 is a horizontal section, similar to FIG. 2(c), schematically illustrative of a rectangularly shaped multi-metallic billet for sheet fabrication.

Referring to the drawing, and particularly to FIGS. 1 and 2, there is schematically and exemplarily illustrated features of certain of the sequenced steps employable, in accord with the principles-of this invention, in the fabrication of composite multi-alloy billets for the extrusion of selectively clad aluminum base alloy products. To the above ends, and as shown in FIG. 1(a), an open ended, elongate and thin walled hollow partition member conveniently in the form of a cylindrical tube of circular cross-section is co-axially disposed within a closed end deformable shell 12 of a second predetermined cross-sectional configuration. In the illustrated structure, the shell 12 is also of circular cross-section to ultimately form a cylindrical billet and is of a length generally commensurate with that of the partition tube 10. Such co-axial disposition of the open ended tube 10 within the closed end shell 12 with the dependent open end 14 thereof disposed in abutting relation with the closed end defining wall portion 16 of the deformable shell 12 results in the formation of a pair of discrete powder receiving cavities or receptacles 18 and 20 therewithin. The core or interior cavity 18 is entirely defined by the tube 10 and the wall 16 and is definitive of a cylinder of circular cross-section. The second cavity 20 is conjointly defined by the positional disposition of the outer wall surface of tube 10 relative to the inner wall surface of shell 12 and in the illustrated embodiment comprises an annulus of uniform thickness.

The outer deformable shell 12 is suitably of the type conventionally employed in hydrostatic compaction apparatus and may be formed of rubber or deformable resinous material, such as polypropylene, polyvinyl chloride and the like. The removable thin walled partition member 10 may be constituted by any suitable material of sufficient strength and rigidity as to resist deformation and displacement during the powdered metal filling operations as hereinafter will be described, and may be conveniently formed of aluminum or steel sheet or of relatively rigid resinous material.

After selective positioning of the partition member 10 within the deformable shell 12 as described above to define metal receiving cavities of predetermined desired configuration, and as shown in FIG. 2(b), a first discrete metallic constituent in the form of finely divided aluminum base alloy powder 22 of a first predetermined metallurgical character is selectively introduced into the cavity 18 to substantially fill the same. Either simultaneously or sequentially with respect thereto, a second discrete metallic constituent in the form of finely divided aluminum base alloy powder metal 24 of a second and different metallurgical character from that of the first metallic constituent is selectively introduced into the second cavity 20 to substantially fill the same. When so filled, the outer shell 12 and its contents may be subjected to light jarring or tamping so as to effect a preliminary gravity induced compaction of the introduced metal particles within the cavities 18 and 20.

For the purposes of this application the terminology discrete metals and difierent metallurgical character" and the like is intended to broadly encompass metalcontaining constituent materials having any ascertainable metallurgical difference therebetween and which are capable of ultimately providing an acceptably bonded interface therebetween and thus to include utilization of dissimilar metals, such as copper, steel or aluminum as well as alloys, such as utilization of two or more recognized alloys of aluminum. Also, as used herein, the term aluminum base alloy" is intended to encompass all such alloys in which the major proportion, i.e., 50 percent or greater, is aluminum.

Following the above, and as shown in FIG. 1(c), the partition member 10 is then removed from the shell 12 by lineal displacement along its longitudinal axis, as indicated by the arrow 26, in such a manner as to effect a minimal disturbance of the metal particles disposed in proximity to the inner and outer surface thereof. Such displacement of the partition tube 10 serves to introduce the particles of the discrete metal powders therefore disposed in abutting facing relation with the inner and outer surfaces of such partition tube 10 into intimate interfacially engaged relation, as illustrated by the dotted lines 28. Complete removal of the partition tube 10 results in the formation of a composite and uncompacted multi-metal powder preform as illustrated in FIG. 2(d) consisting of a cylindrical core of a first aluminum base alloy 22 disposed within a surrounding annulus of a second aluminum base alloy 24. The deformable shell 12 is then conventionally sealed, as by the cap 30, and, after evacuation, subjected to hydrostatic pressure in a suitable press to effect isostatic compaction of the shell 12 and its composite multimetal powdered fill by conventional techniques as for example generally disclosed in US. Pat. Nos. 3,313,871 and 3,608,026. Such isostatic compaction operates to effect a marked increase in the density of the compact and in a uniform reduction of its size, as generally illustrated in FIG. 1(e), without appreciable change in the relative physical positional disposition, both internally and externally, of the now compacted aluminum base alloys 22a and 24a, one to the other.

In the preferred practice of the subject invention, as indicated above, compacted composite multi-alloy billets are formed of aluminum base alloys for the extrusion of selectively clad aluminum base alloy products. By way of illustrative example, and for the fabrication of cylindrically shaped billets of about 7 inch outside diameter and about 12 inches long, the core defining elongate partition tube 10 may be filled with 5056 alloy powder and the cladding defining annular cavity 20 filled with 6253 cladding powder. After removal of the core tube 10, sealing of the shell 12 and evacuation thereof, the shell 12 and its contents were subjected to unit hydrostatic pressures in the order of 32 ksi. The resulting cylindrically shaped compacts were of the character described above and were sufficiently selfsupporting to permit machining and normal handling thereof preparatory to extrusion. These composite compacts were subsequently heated to extrusion temperature which is not only well below any sintering temperature therefore, but also concomitantly provided a degree of degassing thereof. While at extrusion temperature, the compacted billets were conventionally extruded into satisfactory 2 7/8 inch round corner, square alclad bars. The resulting product appeared to have interparticle bonds of nominally the same strength as those present in extrusions from composite billets fabricated in accord with conventional practice. Subsequent examination of such extruded product showed the maintained presence of a distinct line of demarcation between the two aluminum base alloy constituents thereof and without any ascertainable intermixing or infiltration of one alloy into the other. The particles of the two alloys at the interface appeard to be joined to each other in the same manner as would be effected by particles of the same alloy.

FIG. 3 illustrates the permitted utilization of an elongate, thin walled partition member 40 of rectangular cross-section within a deformable shell 42 of circular cross-sectional configuration. Operations as described above will result in the provision of a composite billet having a rectangular core portion 44 of a first metal constituent and a discrete outer or cladding portion 46 of a second metal constituent of a generally annular configuration but with dissimilarly shaped inner and outer surfaces thereof.

FIG. 4 schematically illustrates the application of the principles of this invention to the fabrication of a composite rectangularly shaped billet. In this embodiment, an elongate thin walled planar partition member of rectangular cross-section 50 is coaxially disposed in v v uniform spaced relation within a larger and rectangularly shaped deformable shell 52 and serves to cooperatively define a rectangular central or core cavity 54 and a surrounding peripheral cladding cavity 56 of generally uniform thickness. lntroduction of discrete aluminum base alloy powders of differing metallurgical character into the core cavity 54 and into the cladding cavity 56, followed by removal of the partition 50 and isostatic compaction, as described above, results in the formation of a compacted fillet of rectangular configuration particularly adapted for rolling operations in the fabrication of clad sheet product.

Billets of the above character and of about 6 inches square by about 19-19 A inch long have been readily fabricated by the described technique from 5056 and 6253 aluminum base alloy powders and employing unit hydrostatic pressures of about 21-23 ksi.

Having thus described my invention, I claim:

1. in the formation of composite multi-rnetallic billets for the fabrication of selectively clad metal products, the steps of positioning an elongate, hollow open-ended and relatively thin-walled core member of a first predetermined configuration within a closed-end deformable outer shell member of larger transverse dimension and of substantially commensurate length therewith with one open end of said core member disposed in abutting relation with the closed-end defining wall portion of said shell member to define a plurality of powdered metal receiving cavities therein, introducing a first finely divided metal powder material into a cavity defined by and disposed intermediate said core member and said shell member in sufficient quantity to substantially fill the same,

introducing a second finely divided metal powder material of metallurgical characteristics different from those of said first powder material into a second cavity disposed within and defined by said hollow core member in sufficient quantity to substantially fill the same,

axially removing said core member from said shell member to introduce the particles of said first and second discrete metal powders disposed in abutting relation with the inner and outer surfaces of said core member into intimate interfacially engaged relation without substantial disturbance in the physical positional disposition thereof relative to each other,

sealing said deformable shell member.

and isostatically said sealed deformable shell member and its contents to hydrostatic pressure to compact said powder metal contents thereof to a predetermined desired density without appreciable change in the relative physical positional disposition of said first metal material to said second metal material.

2. The method as set forth in claim 1 wherein said first and second finely divided metal powder materials are aluminum base alloys.

3. The method as set forth in claim 2 including the step of heating said compacted multi-alloy billet to extrusion temperature and extruding the same to form a selectively clad aluminum base alloy product of predetermined configuration.

4. The method as set forth in claim 1 wherein said core member and said shell member are of similar cross-sectional configuration.

5. The method as set forth in claim 1 wherein said core member and said shell member are of different cross-sectional configuration.

6. The method as set forth in claim 2 wherein said thin walled core member and said deformable shell member are of circular cross-sectional configuration, to provide a compacted billet having a cylindrical core and an annular layer of cladding metal enclosing the same.

3,780,418 Dated December 25, 1973 Patent No.

Alvin L. Hurst lnventor(s) I L In cert] I [ed that: error appears in the nbove-l lcnL I Hod patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 23, "The" should read This Column 2, line 66, "empolyable" should read employable Column 3, line 12, "drawing" should read drawings Column 4,

line 65, "therefore" should read therefor Column 5, line 38 "fillet" should read billet 1 line 42 "inch" 5' should read inches Column 6, line 26, after "isostatically" insert subjecting Signed and sealed this 12th day of November 1974.

(SEAL) Attest:

MCCOY M. GIBSON JR. C. MARSHALL DANN Attesting Officer Commissioner of'Patcnts FORM P0405) ($69) USCOMM-DC 60376-P69 U.5. GOVERNMENY PRIN'IING OFFICE 1 869.. 930

, UNITED STATES mm OFFICE CERTIFICATE CORRECTION patent 3,780,418 Dated December. 25, 1973 Alvin L. Hurst I L In cert I [led that. error appears in the above-[dent I fled patent and that said Letters Patent are hereby corrected as shown below:

Column 1 line 23, "The" should read This Column 2 line 66 "empolyable" should read employable Column 3, line 12, "drawing" should read drawings Column 4, line 65, "therefore" should read therefor Column 5, line 38, "fillet" should read billet I line 42 "inch" 5' should read inches Column 6, line 26, after "isostatically" insert subjecting A Signed and sealed this 12th day of November 1974.

(SEAL) Attest:

MCCOY M. GIBSON JR. C. MARSHALL DANN Attesting Officerv Commissioner of Patents USCOMM-DC 603764 69 u.s4 covzmmzm Pmmmc OFFICE: 8 930 FORM PO-1050 (10-69) 

1. In the formation of composite multi-metallic billets for the fabrication of selectively clad metal products, the steps of positioning an elongate, hollow open-ended and relatively thinwalled core member of a first predetermined configuration within a closed-end deformable outer shell member of larger transverse dimension and of substantially commensurate length therewith with one open end of said core member disposed in abutting relation with the closed-end defining wall portion of said shell member to define a plurality of powdered metal receiving cavities therein, introducing a first finely divided metal powder material into a cavity defined by and disposed intermediate said core member and said shell member in sufficient quantity to substantially fill the same, introducing a second finely divided metal powder material of metallurgical characteristics different from those of said first powder material into a second cavity disposed within and defined by said hollow core member in sufficient quantity to substantially fill the same, axially removing said core member from said shell member to introduce the particles of said first and second discrete metal powders disposed in abutting relation with the inner and outer surfaces of said core member into intimate interfacially engaged relation without substantial disturbance in the physical positional disposition thereof relative to each other, sealing said deformable shell member. and isostatically said sealed deformable shell member and its contents to hydrostatic pressure to compact said powder metal contents thereof to a predetermined desired density without appreciable change in the relative physical positional disposition of said first metal material to said second metal material.
 2. The method as set forth in claim 1 wherein said first and second finely divided metal powder materials are aluminum base alloys.
 3. The method as set forth in claim 2 including the step of heating said compacted multi-allOy billet to extrusion temperature and extruding the same to form a selectively clad aluminum base alloy product of predetermined configuration.
 4. The method as set forth in claim 1 wherein said core member and said shell member are of similar cross-sectional configuration.
 5. The method as set forth in claim 1 wherein said core member and said shell member are of different cross-sectional configuration.
 6. The method as set forth in claim 2 wherein said thin walled core member and said deformable shell member are of circular cross-sectional configuration, to provide a compacted billet having a cylindrical core and an annular layer of cladding metal enclosing the same. 